The part of a cell that gives the cell unique characteristics is the
a) nucleus.
b) vacuole.
c) cytoplasm.
d) membrane.

A) Nucleus

The nucleus of a biological cell contains the genetic information that is used to create the proteins within the cell, and, in the case of multicellular organisms, proteins outside of the cell as well. This is why the nucleus contains the "identity" of the cell since it has all of the information required to create the cell. Therefore, the nucleus provides the unique characteristics. 

Most likely a is the answer - because  you generate   38 atp's but also consume an atp.   each atp gives approx. less than 4 kcal so probably a is the closest answer.